Air Conditioning - Compressor bad?

Hey, I was checking a compressor that was tripping the breaker. I took off all the wires at the compressor. when I touched one of my meter leads to a compressor terminal and the other lead to the copper tubing the meter showed resistance but the continuity beeper didn't beep. If the meter shows any resistance does that mean the compressor is grounded, even though my meter didn't beep for continuity?

Your compressor is shot. I would now be concerned with possible acid contamination.

I don't think we are allowed to give much more information since an entire thread was deleted regarding compressors.

I don't think we are allowed to give much more information since an entire thread was deleted regarding compressors.

I believe there was some possible misunderstanding regarding the thread I coincidently started under the same title. The presumption was that my thread dealt with "commercial", and this forum is not for commercial stuff, to my understanding, now.

But it so happens that even though in my case the application was for a small business in a strip mall - the unit I was so desperately trying to get information on was really a unit just like that on homes: Regular furnace/air handler in a room in the lady's shop and up on the roof (as opposed to outside along some house) was a single phase Goodman condenser unit that was actually very simple. I thought questions I asked in that thread could also help others with problems on their own home units.

As you recall, I listed only a single handful or things this unit consisted of. And I so much wanted to get that thing going if I could, to help that lady, as our HVAC guy could not make it there, as he had 18 calls in front of us.

So it might not be the issue were you are trying to help people out with compressors, or at least answer their questions. (Keep in mind moderators are helping posters out solve their electrical woes on those types of forums here.) If I'm wrong on this, I'm sure I'll be corrected.

Hmmmm. Your post seemed clear the equipment was of residential type in a commercial setting. Single phase, equals 5 tons or less, equals the range of residential.

Not really a problem, I can answer future questions in a vague way or suggest they call a technician (or not post at all). Kind of defeats the "do it yourself" theme, however.

It is a Goodman 4 ton. Tried the "kick start" (hard start) capacitor in series with my capacitor (so that they were on the 2 correct terminals for the compressor and not on the cap terminals for the fan) and this did not help start it. No difference in sound, either. The 2-30A breaker does not trip out. The buzzing simply stops after I presume the overload inside the compressor kicks off. The "kick start" was good for 5 ton or 10 horsepower units, adn says it increases torque by 300%). I had full 240 voltage thru contactor and on the compressor terminals itself, and and proper ohms that added up correctly on the 3 compressor terminals. Wires go directly from terminals to capacitor and run wires, with no additional relays or pressure switches. Simple unit. No HVAC guy has been there, so that rules out overcharging the system. The system was putting out real cold air the day before, according to shop owner. Then nothing but buzzing, and then even that "dtdtdtdtdt" sound from the compressor. The condensor fan would come right on with call for cold, but not the compressor. Dual cap for fan and compressor/;no bulge and motor shop man tested it good. Found non-odor producing oil at bottom of unit. Old, with dust on top of it. The condensor coils pass through a galvanized metal shroud that divides the contactor-capacitor-compressor compartment from the coils compartment, and it looks like some electrolysis may have occured with white froth where the two dissimilar metals touch, and the bottommost copper coil had some oil on it.

Could enough refrigerant/oil have leaked out, that over time, this ended up ruining the compressor mechanically, rather than electrically, inside?

If the compressor were seized, the motor should draw enough amps to trip the breaker. Goodmans are, or at least were in the past, notorious for burning off compressor wires. Next time you are there, check amp draw.

I do have an amp meter. I'd assume wires burned off INSIDE the compressor? (which if so would mean compressor is shot), as any exterinal wire from the 3 compressor terminals are all out in the open, from common, cap, etc., and are all showing correct voltage at the terminals on the compressor. I presumed that the reason the buzzing sound stopped is that some overload circuit in the compressor opens up before the breaker trips. More thoughts?

But for the fun of it, I may run over there and check this out. I should have in the first place, I guess.

Our HVAC guy wasn't there yet as of yesterday, and the shop owner lady has been staying as cool as she can by utilizing the windtunnel effect with front and back door open through the narrow shop.

Any resistance between a comp terminal and ground (the copper tube) is a short to ground.

Have it replaced by qualified service tech.

Any resistance between a comp terminal and ground (the copper tube) is a short to ground.

Have it replaced by qualified service tech.

I don't have that, though.

Grady,

Just got back from the roof, 2 miles away. The voltage at contactor = 239 volts. The voltage at the compressor terminals is 227 when it just buzzes, but as the fan comes on at the same time as the compressor buzz sound, the voltage reads 239. Huh! I did the test twice to make sure I had good contact. Same result. But 227 should be good enough anyway, right?

The nameplate on the Goodman says 45 amps maximum for breaker, and the RLA listing is 20.0 and the LRA listing is 110.0. My ampmeter reading, while I held in the contactor, was 110, while it buzzed. The buzzing will stop without throwing the breaker, if left on.
(No typos on these numbers, and the range setting was correct on my meter, at 600A setting. At first I tried the 60 A range setting, and my needle flew off the chart. :))
It almost seems like the capacitor is bad, doesn't it? Yet, the capacitor was checked out by motor shop, who could have just as easy sold me a new one, and no leaking or bulge, and even with the kickstart hard start cap installed in series, that made no difference.

Or, this business about too much pressure, that for some reason is surfacing? Maybe some stuck check valve in compressor?, as a possiblity where the hiogh pressure built up and won't come back down, let's say?

I can tell the HVAC guy WAS there as a screw was left off the cover and one side was somewhat ajar. I did not have it that way, the last time I was up there. Either he did it that way to see if I was still up there messing with it, or he was careless. I would not doubt either, especially the latter, as I have seen him do things quickly, and with anger, like rip out a dirty stuck filter, while I stood there watching him once, which is pretty dumb, IMO, as all the dust redeposits back in the unit. :thumbdn:

when I touched one of my meter leads to a compressor terminal and the other lead to the copper tubing the meter showed resistance but the continuity beeper didn't beep.

You don't have what? You first siad compressor terminal to copper equals resistance. That would be a short.

I believe the compressor is going out on internal overload before it can trip the breaker. Pure speculation on my part without being able to get my hands & eyes on it.

ecman51`Member You said: "It is a Goodman 4 ton. Tried the "kick start" (hard start) capacitor in series with my capacitor"


*It must be in parallel with the run cap .. to work!

*sometimes in some types of compressor configurations, you can read high resistance values from winding to case/copper lines because of the type of oil in the system ( I think POE type - not sure)and condition of the oil carbons as it is in some varying degree a state of burn (as the oil touches the windings and the hermetic case at the same time). It is rare, and irrelevant.

ecman51`Member You said: "It is a Goodman 4 ton. Tried the "kick start" (hard start) capacitor in series with my capacitor"


*It must be in parallel with the run cap .. to work!



Sorry, I used wrong term. I did as instructions and left capacitor wires connected and I connected up WITH them. That would be in parallel. Sorry.

Did ecman51` originally start this thread logged in as theapprentice? Or has he just jumped in and hyjacket it?

Did ecman51` originally start this thread logged in as theapprentice? Or has he just jumped in and hyjacket it?


Hijacked.

But its cool, any learning is good learning. :thumbup:

Ok,
As long as your still there and are learning, I'm for it.

Did ecman51` originally start this thread logged in as theapprentice? Or has he just jumped in and hyjacket it?

No. I'm just ecman, only. Kind of good fortune it reappeared. Hopefully this thread may help others also, as this system is basically a home-type system: Furnace/airhandler inside, and the condensor unit outside.

Check out the Compressor Handbook here:
http://202.56.127.90/nacg/service_data.php#

Or download the enitre thing here:
http://jarredsdad.embarqspace.com/#/welcome/4529420987

It's almost 4Mb and 140 pages if you print.

Also have one for Carlyle Compressors, but it's more Carrier Commercial compressors.

apprentice, read and learn. Ref books are great tools to have on your truck, or laptop if you carry one.

MY clue today was seeing the shop's door closed, in this heat we are having. So I stopped in, and - ahhhhhhh - A/C! Somebody replaced the rooftop unit with another new Goodman. I am guessing that even if I find out who did the work and ask them what was wrong with the old compressor, they'd probably just say it was 'locked up'. The old unit was a '92 and it looked like they designed it bad from the standpoint they ran the copper tubes through and tight against the galvanized sheetmetal divider. And it looked like there was oil on the bottom copper loop, as well as the bottom of the unit.